docs: def get_release_date(pdb_id):
      """Quick way to get the release date of a PDB ID using the table of results from the REST service
  
      Returns None if the release date is not available.
  
      Returns:
          str: Organism of a PDB ID
  
      """
  
      pdb_id = pdb_id.upper()
      if pdb_id not in _property_table().index:
          raise ValueError('PDB ID not in property table')
      else:
          release_date = _property_table().ix[pdb_id, 'releaseDate']
          if pd.isnull(release_date):
              log.debug('{}: no release date available')
              release_date = None
  
      return release_date